Print heads for ink jet printers are precisely manufactured so that the components cooperate with an integral ink reservoir to deliver ink to an ink ejection device in the print head to achieve a desired print quality. A major component of the print head of an ink jet printer is the nozzle plate which contains ink supply channels, firing chambers and ports for expelling ink from the print head.
Since the introduction of ink jet printers, nozzle plates have undergone considarable design changes in order to increase the efficiency of ink ejection and to decrease their manufacturing cost. Changes in the nozzle plate design continue to be made in an attempt to accommodate higher speed printing and higher resolution of the printed images.
Although advances in print head design have provided print heads capable of printing with increasingly finer resolution at higher print speeds, the improvements have created new challenges with respect to manufacturing the nozzle plates because of the increase in the complexity of the designs. Accordingly, with more complex flow feature designs, problems that were previously insignificant have become serious detractions in print head reliability and have affected production quality.
For example, when print heads had larger flow channels and nozzle holes, debris in the ink was able to more easily pass through the parts of the ink jet print head, eventually passing out of the print head through the nozzle without creating a problem. Now, however, several of the parts within a print head are much narrower and thus tend to trap debris in the ink flow areas rather than let the debris pass through unimpeded. Trapped debris may result in a nozzle which can no longer receive ink, thus impacting the print quality of the print head.
Filters of various configurations have been used to attempt to catch the debris before it encounters a part within the print head that is too narrow for the debris to pass. Unfortunately, such filters typically either add expensive additional processing steps to the manufacture of the print heads, or produce more resistance to the flow of ink than is necessary to perform the function of filtering, thus creating other problems with the use of the filter.
One filter design is provided in U.S. Pat. No. 5,463,413 to Ho et al. which describes a barrier reef design comprised of pillars formed from the barrier layer attached to the semiconductor substrate. The spacing between the pillars is designed to support a separate nozzle plate and to filter out particles from the ink before the particles reach the barrier inlet channels. In this design, separate nozzle plates and barrier layers are formed which increases production costs and reduces the accuracy and precision required for improved printing.
It is an object of this invention, therefore, to provide improved nozzle plates for ink jet print heads.
It is another object of this invention to provide a method for reducing manufacturing problems associated with the nozzle plate design.
It is a further object of this invention to provide nozzle plates for ink jet printers which possess improved ink filtering characteristics in order to trap debris.
Still another object of the invention is to provide a method for manufacturing nozzle plates for ink jet printers having improved flow characteristics.